Auxin Levels Research Articles

Natural variation of OsWRKY23 drives difference in nitrate use efficiency between indica and japonica rice

Between the two major rice subspecies, indica varieties generally exhibit higher nitrate (NO3‒) uptake and nitrogen (N)-use efficiency (NUE) than japonica varieties. Introducing efficient NO3‒ utilization alleles from indica into japonica could improve NUE, and at the same time uncover unknown regulators of NO3‒ metabolism. Here, we identify OsWRKY23 as a key regulator of NO3‒ uptake and NUE differences between indica and japonica rice. The OsWRKY23indica allele exhibits reduced transcriptional activation of a negative regulator of auxin accumulation, DULL NITROGEN RESPONSE1 (DNR1). The resultant increase in auxin level improves NO3‒ uptake and assimilation, which ultimately enhances grain yield. Geographical and evolutionary analyses reveal overlapping distribution of OsWRKY23indica and DNR1indica, particularly in low-fertility soils, suggesting their involvement in the adaptation to low N conditions to improve NUE and grain yield. Incorporating the OsWRKY23-DNR1 module from indica rice represents a promising strategy to enhance japonica NUE, which is crucial for sustainable agriculture.

Melatonin improves the lead tolerance in Plantago ovata by modulating ROS homeostasis, phytohormone status and expression of stress-responsive genes.

Melatonin increases Pb tolerance in P. ovata seedlings via the regulation of growth and stress-related phytohormones, ROS scavenging and genes responsible for melatonin synthesis, metal chelation, and stress defense. Lead (Pb) is a highly toxic heavy metal that accumulates in plants through soil and air contamination and impairs its plant growth and development. Because of its pharmaceutical importance, improvements in Plantago ovata yield against abiotic stresses are necessary. Melatonin (MEL) is a stress-alleviating biostimulator and our results showed a reduction in Pb induced phytotoxicity by enhancing plant growth attributes and balancing protective osmolytes. Pb-induced reactive oxygen species accumulation, including superoxide and peroxide free radicals and their mitigation through enzymatic antioxidants, was demonstrated in presence of MEL. Cell viability and Pb bioaccumulation were determined to understand the extent of cellular damage. Moreover, MEL increased secondary metabolite (flavonoids and anthocyanins) contents by 2-3-fold at the lowest Pb concentrations. Similar increases in the relative expression of genes (PoPAL and PoPPO), which are responsible for the production of non-enzymatic antioxidants, were observed. Notably, the upregulation of the PoCOMT gene up to 4-fold indicates increased melatonin production, as manifested in the phytomelatonin level. MEL supplementation also increased the auxin (IAA) level by 3-fold in the 100µM Pb treatment group, while the abscisic acid (ABA) level decreased (1.4-fold) and the expression of PoMYB (a stress-related transcription factor) increased (up to 2.66-fold). Additionally, we found extreme downregulation (up to 18-fold) in the relative expression of PoMT 2 (a metal binding thiol compound) with melatonin treatment, which is otherwise upregulated (by 6-fold) during Pb stress. In the current study, these effects collectively revealed that MEL contribute to enhanced plant growth and Pb stress tolerance.

Auxin treatment reduces inflorescences number and delays bud development in the alternate bearing Citrus cultivar Murcott mandarin.

Specific cultivars of many commercial fruit tree undergo cycles of heavy fruit load (ON-crop) one year, followed by low fruit load (OFF-crop) the next (termed alternate bearing). Fruit load may affect flowering at various developmental stages, and its presence is suggested to generate a flowering-inhibitory signal. In a previous report, we showed that the presence of fruit induces polar auxin transport from the fruit into the stem, interfering with indole acetic acid (IAA) release from the bud, and thus elevating its levels in the bud meristem. To better understand the relationship between auxin homeostasis in the bud and flowering, IAA or 2,4-Dichlorophenoxyacetic acid (2,4-D) were applied with the polar auxin transport blocker 2,3,5-triiodobenzoic acid (TIBA) to OFF-crop 'Murcott' mandarin trees during the flowering-induction period. The treatment reduced inflorescences number and delayed bud development. Transcriptome analysis following the treatment revealed a reduction in the expression of a few flowering-control genes, including LEAFY and SQUAMOSA PROMOTER BINDING PROTEIN-LIKE. In addition, genes related to carbohydrate metabolism were reduced. We suggest that the elevation of auxin levels in the bud by heavy fruit load directly affects the expression of flowering-control, flower-development, and developmental genes.

Effects of exogenous SLs on growth and physiological characteristics of flue-cured tobacco seedlings under different degrees of drought stress.

Drought stress severely affects global crop yields, reduces water availability, and hinders growth. Strigolactones can alleviate damage caused by various abiotic stresses in plants; however, limited research has been conducted on their ability to enhance drought tolerance in tobacco. This study evaluated the drought tolerance of 'Qin Tobacco 96' (drought-tolerant) and 'Yun Tobacco 116' (moisture-sensitive) before and after the application of gibberellic acid lactone at a concentration of 0.2 mg·L⁻¹ under three drought conditions: mild, moderate, and severe. The primary drought tolerance traits were identified from 29 related indicators, including agronomic traits, photosynthetic efficiency, reactive oxygen metabolism, antioxidant enzyme activities, osmotic regulators, and hormone regulation, using affiliation function, principal component analysis, and cluster analysis to categorize the traits. The degree of drought tolerance enhancement in the two tobacco varieties was evaluated under various treatments. Spraying exogenous strigolactones reduced the adverse effects of drought stress, particularly in the moisture-sensitive Y116 variety. Under drought stress, chlorophyll content and photosynthetic parameters significantly decreased, whereas strigolactone treatment increased both chlorophyll content and photosynthetic efficiency. Strigolactones reduced the accumulation of reactive oxygen species and malondialdehyde content, enhancing the antioxidant capacity of both varieties. Additionally, strigolactones increased the levels of osmoregulatory substances and activated the production of antioxidant enzymes, thereby enhancing drought tolerance. Furthermore, drought stress disrupted the balance of endogenous hormones, decreasing levels of auxin, gibberellic acid, and ribosylzeatin, while increasing abscisic acid levels. Exogenous strigolactones restored this hormonal balance. Sixteen traits associated with drought tolerance in tobacco were analyzed using principal component analysis, the traits were classified using cluster analysis, and the magnitude of the D-value was determined by calculating the values of the affiliation function and their respective weights. The results indicated that a concentration of 0.2 mg·L⁻¹ of strigolactones enhanced the drought tolerance of tobacco across different levels of drought stress and promoted the growth and development of flue-cured tobacco. However, the interactions between strigolactones and various hormones under drought stress require further investigation to elucidate the underlying molecular mechanisms. The application methods of strigolactones should be optimized.

Auxin fluctuation and PIN polarization in moss leaf cell reprogramming.

Auxin and its PIN-FORMED (PIN) exporters are essential for tissue repair and regeneration in flowering plants. To gain insight into the evolution of this mechanism, we investigated their roles in leaves excised from Physcomitrium patens, a bryophyte known for its remarkable cell reprogramming capacity. We used various approaches to manipulate auxin levels, including exogenous application, pharmacological manipulations, and auxin biosynthesis mutants. We observed no significant effect on the rate of cell reprogramming. Rather, our analysis of auxin dynamics revealed a decrease in auxin levels upon excision, which was followed by a local increase before the reprogramming process began. Mutant analysis revealed that PpPINs are required for effective cell reprogramming, and endogenously expressed PpPINA-GFP accumulates polarly at sites that will develop into future filamentous stem cells. In addition, hyperpolarized PpPINA variants carrying mutated phosphorylation sites showed a marked delay in reprogramming, whereas endogenous or non-polar versions do not have this effect. These results underscore that both, the levels and the polarity of PpPINA are important for efficient cell reprogramming. Overall, these findings highlight the pivotal role of PIN polarity in plant regeneration. Furthermore, they suggest that understanding polarity mechanisms could have broader implications for improving regenerative processes across various plant species.

Comparative effects of Serendipita indica and a mix of arbuscular mycorrhizal fungi on the growth, photosynthetic capacity, and proteomics of Schinus terebinthifolius Raddi.

Both, Serendipita indica and AMF, show promise as sustainable biofertilizers for reforestation, improving nutrient uptake and stress tolerance, despite contrasting effects on photosynthetic capacity and biomass allocation. Reclaiming degraded areas is essential for biodiversity conservation and enhancing ecosystem services enhancement, especially when using native species. This study investigated Schinus terebinthifolius Raddi, a native Brazilian species, and its compatibility with plant growth-promoting microorganisms (PGPM), including an endophytic fungus (Serendipita indica) and a consortium of arbuscular mycorrhizal fungi (AMF), to identify effective strategies for reforestation in nutrient-poor environments. We observed growth stimulation by both PGPMs; however, S. indica primarily enhanced root weight, whereas AMF improved shoot weight. S. indica's positive effects on root systems could be attributed to increased auxin levels and altered root architecture, which are critical for seedling establishment in reforestation programs. In terms of nutritional status, both treatments increased the content of most nutrients, with higher micronutrient contents in the shoots and higher macronutrient content in roots of inoculated plants. Despite AMF's role in enhancing photosynthesis, plants inoculated with these fungi showed reduced photosynthetic capacity traits, possibly due to lower leaf nitrogen content. The proteomic analysis of Schinus terebinthifolius leaf extracts revealed that, despite the upregulation of several proteins associated with the photosynthetic apparatus in response to S. indica treatment, no enhancement in photosynthetic capacity was observed. We also found several proteins related to oxidative stress in plants inoculated with both fungi, indicating a greater tolerance to adverse environmental conditions. These findings underscore the potential of both, S. indica and AMF, as sustainable alternatives to chemical fertilizers in reforestation efforts, enhancing seedling quality and survival in nutrient-poor soils.

Transcriptome Analysis and Phytohormone Profile Reveal Core Phytohormone Regulating Parthenocarpy in Fingered Citron

Background: Parthenocarpy, the development of fruit without fertilization, is a significant trait in fingered citron (Citrus medica L. var. sarcodactylis Swingle). This study aims to elucidate the regulatory mechanisms underlying parthenocarpy through comparative transcriptome analysis and phytohormone profiling between fingered citron and its non-parthenocarpic counterpart, citron. Results: A total of 66 differentially expressed hormone-related genes were identified, with the auxin pathway emerging as the most prominent in fingered citron. Protein–protein interaction analysis revealed a potential interaction between auxin and abscisic acid (ABA). Phytohormone content analysis indicated that fingered citron exhibited higher levels of indole-3-acetic acid (IAA) and lower levels of ABA compared to citron. A weighted gene co-expression network analysis (WGCNA) suggested that the interplay between auxin and ABA is crucial for triggering parthenocarpy. Virus-induced gene silencing (VIGS) experiments demonstrated that silencing CmsABI5 led to decreased ABA levels, while auxin levels remained unchanged, resulting in disrupted parthenocarpy and increased ethylene levels, indicating a secondary hormonal response. Additionally, gene expression changes associated with failed parthenocarpy showed down-regulation of SAUR50 and up-regulation of PP2C 56, linking these changes to ABA signaling. Conclusions: Our findings highlight the central regulatory role of auxin in parthenocarpy in fingered citron, with ABA acting as a critical modulator. The suppression of ABA alone disrupts parthenocarpy despite stable auxin levels, emphasizing the necessity of balanced hormone interactions. This research underscores the significant role of auxin, rather than gibberellin (GA), in regulating parthenocarpy in fingered citron, contributing valuable insights to the understanding of fruit development mechanisms.

Metabolic and transcriptional analysis of tuber expansion in Curcuma kwangsiensis

The tubers of Curcuma kwangsiensis are regarded as an important medicinal material in China. In C. kwangsiensis cultivation, tuber expansion is key to yield and quality, but the regulatory mechanisms are not well understood. In this study, metabolomic and transcriptomic analyses were conducted to elucidate the mechanism underlying tuber expansion development. The results showed that auxin (IAA), jasmonic acid (JA), gibberellin (GA3), ethylene (ETH), and brassinolide (BR) levels increased during tuber expansion development. Metabolomic analysis showed that 197 differentially accumulated metabolites (DAMs) accumulated during tuber expansion development and these also play important roles in the accumulation of carbohydrates and secondary metabolites. 6962 differentially expressed genes (DEGs) were enriched in plant hormone signal transduction, starch and sucrose metabolism, linoleic acid metabolism, MAPK signaling pathway as well as sesquiterpenoid and triterpenoid biosynthesis. Comprehensive analysis revealed that DEGs and DAMs of plant hormone signal transduction, ABC transporters and biosynthesis of phenylpropanoids and terpenoids are critical pathways in regulating tuber expansion. In addition, some transcription factors (ARF, C2H2, C3H, NAC, bHLH, GRAS and WRKY) as well as hub genes (HDS, HMGR, ARF7, PP2CA, PAL and CCOMT) are also involved in this process. This study lays a theoretical basis for the molecular mechanism of tuber expansion in C. kwangsiensis.

ABA-auxin cascade regulates crop root angle in response to drought.

Enhancing drought resistance through the manipulation of root system architecture (RSA) in crops represents a crucial strategy for addressing food insecurity challenges. Abscisic acid (ABA) plays important roles in drought tolerance; yet, its molecular mechanisms in regulating RSA, especially in cereal crops, remain unclear. In this study, we report a new mechanism whereby ABA mediates local auxin biosynthesis to regulate root gravitropic response, thereby controlling the alteration of RSA in response to drought in cereal crops. Under drought conditions, wild-type (WT) plants displayed a steep root angle compared with normal conditions, while ABA biosynthetic mutants (mhz4, mhz5, osaba1, and osaba2) showed a significantly shallower crown root angle. Gravitropic assays revealed that ABA biosynthetic mutants have reduced gravitropic responses compared with WT plants. Hormone profiling analysis indicated that the mhz5 mutant has reduced auxin levels in root tips, and exogenous auxin (naphthaleneacetic acid [NAA]) application restored its root gravitropic defects. Consistently, auxin reporter analysis in mhz5 showed a reduced auxin gradient formation in root epidermis during gravitropic bending response compared with WT plants. Furthermore, NAA, rather than ABA, was able to rescue the compromised gravitropic response in the auxin biosynthetic mutant mhz10-1/tryptophan amino transferase2 (ostar2). Additionally, the maize ABA biosynthetic mutant viviparous5 (vp5) also showed gravitropic defects and a shallower seminal root angle than WT plants, which were restored by external auxin treatment. Collectively, we suggest that ABA-induced auxin synthesis governs the root gravitropic machinery, thereby influencing root angle in rice, maize, and possibly other cereal crops.

Excessive accumulation of auxin inhibits protocorm development during germination of Paphiopedilum spicerianum.

Excessive auxin accumulation inhibits protocorm development during germination of Paphiopedilum spicerianum, delaying shoot meristem formation by downregulating boundary genes (CUC1, CUC2, CLV3) and promoting fungal colonization, essential for seedling establishment. Paphiopedilum, possess high horticultural and conservational value. Asymbiotic germination is a common propagation method, but high rates of protocorm developmental arrest hinder seedling establishment. Our study found that the key difference between normally developing protocorm (NDP) and arrested developmental protocorm (ADP) is their capability for continuous cell differentiation. In ADP, cells divide without differentiating, with indole-3-acetic acid (IAA) levels being 20 times higher than that in NDP. This suggests that auxin level plays a role in protocorm cell fate determination. Exogenous application of NAA demonstrated that elevated auxin level can delay the formation of the shoot apical meristem (SAM) inside the protocorm. Gene expression analysis revealed that elevated auxin can inhibit or even halt the SAM formation through down-regulation of SAM-related genes such as CLV3, CUC1 and CUC2. High auxin levels also led to reduced cell wall rigidity by up-regulation of cell wall expanding protein (EXPB15), thereby creating ideal conditions for fungi entry. Inoculation with a compatible orchid mycorrhizal fungus (OMF) resulted in successful cell differentiation of ADP and eventually triggered the conversion of ADP to NDP. Since the protocorm is a distinct structure that facilitates the establishment of symbiotic associations with compatible OMF, we propose that the excessive auxin accumulation inside Paphiopedilum protocorm can pause the further development of protocorm and soften the cell wall. This strategy likely serves to enhance the attraction and colonization by OMFs in the native habitat of Paphiopedilum, facilitating essential symbiotic relationships necessary for their survival and growth.

Feedback regulation of m6A modification creates local auxin maxima essential for rice microsporogenesis.

N6-methyladenosine (m6A) RNA modification and its effectors control various plant developmental processes, yet whether and how these effectors are transcriptionally controlled to confer functional specificity so far remain elusive. Herein, we show that a rice C2H2 zinc-finger protein, OsZAF, specifically activates the expression of OsFIP37 encoding a core component of the m6A methyltransferase complex during microsporogenesis in rice anthers. OsFIP37, in turn, facilitates m6A modification and stabilization of an auxin biosynthesis gene OsYUCCA3 to promote auxin biosynthesis in anthers. This elevates auxin levels coinciding with upregulation of an auxin response factor OsARF12 that positively controls OsZAF, thus creating a positive feedback circuit whereby OsFIP37 is continuously activated for local auxin production. Our findings suggest that OsZAF-dependent feedback regulation of m6A modification is integral to local auxin biosynthesis and signaling in anthers, which facilitates the timely generation of auxin maxima required for male meiosis in rice.

Boron controls apical dominance in Pea (Pisum sativum) via promoting polar auxin transport.

Plant architecture and subsequent productivity are determined by the shoot apical dominance, which is disturbed by the deficiency of boron, one of the essential trace elements for plant growth and reproduction. However, the mechanism by which B controls shoot apical dominance or axillary bud outgrows under B deficiency is still unclear. This work aimed to investigate the mechanistic basis of this process, with focus on the interaction between B and polar auxin transport. Adopting an all-buds phenotyping methodology and employing several complementary approaches, we found that boron deficiency inhibited plant growth and changed the shoot architecture, resulting in the outgrowth of axillary buds at nodes 1-3. This was related to the auxin accumulation in shoot apical parts buds under B deficiency. Applying N-1-naphthylphthalamic acid to inhibit auxin transport from the shoot apex promoted the outgrowth of axillary buds in boron-sufficient (+B) plants. In decapitated plants, the application of exogenous auxin to the shoot apex only inhibited the outgrowth of axillary buds in +B plants. At higher auxin doses, the toxic effect of IAA was observed in the lower part of the shoot, which was more severe in +B plants than in B-deprived (-B) plants. Furthermore, the expression of PsPIN3 was significantly downregulated under -B conditions. These results indicate that B deficiency inhibits PAT from the apical bud through the main stem to the lower parts, leading to an increase of auxin level in the apical bud, which inhibits the growth of apical buds while stimulating the outgrowth of axillary buds.

Ectopic expression of LONELY GUY7 in epidermis of internodal segments for de novo shoot regeneration without phytohormone treatment in ipecac.

In many plant species, the application of exogenous phytohormones is crucial for initiating de novo shoot regeneration. However, ipecac [Carapichea ipecacuanha (Brot) L. Andersson] has a unique ability to develop adventitious shoots on the epidermis of internodal segments without phytohormone treatment. This characteristic allows us to evaluate the effects of endogenous phytohormones in this species. Here, we showed that the presence of the pith, including vascular bundles in the internodal segment, is required to activate both endogenous cytokinin (CK) biosynthesis and adventitious shoot formation. Adventitious shoots were mainly formed in the apical region of internodal segments, where the CK biosynthesis genes ISOPENTENYL TRANSFERASE 3 (CiIPT3) and LONELY GUY 7 (CiLOG7) were spontaneously upregulated in the early culture stage on phytohormone-free medium. In addition, CiIPT3 and CiLOG7 were respectively expressed in the pith and the epidermis of the internodal segments. The expression of CiLOG7 was localized as several spots on the epidermis. These findings suggest that CK precursors are generated in the pith, transferred to the epidermis, and then converted into active CKs, facilitating adventitious shoot formation on the epidermis. Conversely, auxin levels rapidly decreased during culture and remained low in the region of shoot formation. Auxin is transferred to the basal region of internodal segments, and strongly suppressed the CiLOG7 expression and decreased the CK levels. Thus, we conclude that the ectopic expression of CiLOG7 in the epidermis of internodal segments contributes to de novo shoot regeneration in ipecac.

Analysis of the molecular mechanism endogenous hormone regulating axillary bud development in Pinus yunnanensis

BackgroundP. yunnanensis, a distinctive economic tree species native to Yunnan Province in China, possesses axillary buds that serve as superior material for asexual propagation. However, under natural growth conditions, the differentiation of these axillary buds is notably scarce. In this study, we employed decapitation to stimulate the development of axillary buds in P. yunnanensis. Subsequently, we assessed the phytohormone levels in both axillary and apical buds, and conducted a comprehensive transcriptomic analysis complemented by RT-qPCR validation.ResultsWe found that decapitation could effectively promote the releases of the axillary buds in P. yunnanensis. The levels of cytokinin, auxin, gibberellin and abscisic acid in axillary buds were higher than those in apical buds, and the difference in gibberellin levels was the greatest. The transcriptome sequencing results were highly reproducible, and the relative expression levels of the 13 genes screened were highly consistent with the FPKM value trend of transcriptome sequencing. There were 2877 differentially expressed genes (DEGs) between axillary buds and terminal buds, and 18 candidate genes (CGs) involved in axillary bud release were screened out. A total of 1171 DEGs were identified during the analysis of axillary bud growth, and 14 CGs involved in axillary bud growth and development were screened out. GO and KEGG enrichment analysis were performed on the DEGs. Furthermore, combined with the results and discussion, the functions of the candidate genes were analyzed and a possible regulatory network was constructed.ConclusionThe findings and discussions indicated that the development of axillary buds in P. yunnanensis is predominantly governed by cytokinin, gibberellin, strigolactone, and auxin, as well as their biosynthesis and regulatory genes, which are crucial to the development of these buds. This study has, to some extent, bridged the research gap concerning the development of axillary buds in P. yunnanensis and has provided foundational data to support further research into the developmental mechanisms of these buds and the establishment of asexual propagation cutting nurseries.

Desert-adapted plant growth-promoting pseudomonads modulate plant auxin homeostasis and mitigate salinity stress.

By providing adaptive advantages to plants, desert microorganisms are emerging as promising solutions to mitigate the negative and abrupt effects of climate change in agriculture. Among these, pseudomonads, commonly found in soil and in associationwith plants' root system, have been shown to enhance plant tolerance to salinity and drought, primarily affecting root system architecture in various hosts. However, a comprehensive understanding of how these bacteria affect plant responses at the cellular, physiological and molecular levels is still lacking. In this study, we investigated the effects of two Pseudomonas spp. strains, E102 and E141, which were previously isolated from date palm roots and have demonstrated efficacy in promoting drought tolerance in their hosts. These strains colonize plant roots, influencing root architecture by inhibiting primary root growth while promoting root hair elongation and lateral root formation. Strains E102 and E141 increased auxin levels in Arabidopsis, whereas this effect was diminished in IAA-defective mutant strains, which exhibited reduced IAA production. In all cases, the effectiveness of the bacteria relies on the functioning of the plant auxin response and transport machinery. Notably, such physiological and morphological changes provide an adaptive advantage to the plant, specifically under stress conditions such as salinity. Collectively, this study demonstrates that by leveraging the host's auxin signalling machinery, strains E102 and E141 significantly improve plant resilience to abiotic stresses, positioning them as potential biopromoters/bioprotectors for crop production and ecosystem restoration in alignment with Nature-based Solution approaches.

Integrating physiological and transcriptomic analyses explored the regulatory mechanism of cold tolerance at seedling emergence stage in upland cotton (Gossypium hirsutum L.)

Cold stress is one of the major abiotic stressor that profoundly impacts plant growth. Cotton, a widely cultivated variety, is particularly susceptible to cold stress. Unraveling the responses to cold stress is critical for cotton demand. In this investigation, we conducted comparative physiological and transcriptomic analyses of the cold-tolerant variety XLZ16 and cold-sensitive variety XLZ84 at seedling emergence stage under cold stress. Following exposure to cold stress, XLZ16 exhibited a markedly higher growth phenotype and increased activity of antioxidant enzymes, while simultaneously showing reduced cellular oxidative damage and apoptosis. Furthermore, the levels of auxin (IAA), cytokinin (CTK), and salicylic acid (SA) significantly increased during cold stress, whereas the contents of catendorsterol (TY), brassinosterone (CS), and jasmonic acid (JA) significantly decreased. Integrated with stoichiometric analysis, these findings definitively demonstrated significant differences in antioxidant capacity and hormone content between the two varieties during their response to cold stress. A total of 6207 potential cold-responsive differentially expressed genes (DEGs) were identified through transcriptome sequencing analysis. Enrichment analyses of these DEGs revealed that pathways related to “hormones biosynthesis and signaling” as well as “circadian rhythm” were associated with cold response. Notably, the hub gene Gh_D12G2567 (GhJAZ3), encoding jasmonate ZIM-domain (JAZ) proteins, was found to influence the JA signal transduction pathway and regulate cotton growth under cold stress within the MEred module network. Furthermore, suppressing the expression level of GhJAZ3 by virus-induced gene silencing led to the reduction of cold resistance, implying GhJAZ3 as a positive regulator of cold tolerance. This study provides valuable insights into the response mechanisms of cotton under cold stress. It also serves as a reference and foundation for further enhancing cold tolerance of new cotton varieties.

The auxin-like effect of substrate and auxin sensitivity of plant modulate the PGPR activity of Lysinibacillus pinottii sp. nov. PB211

BackgroundBacterial auxin production is a mechanism that promotes plant growth. However, it can also be linked to deleterious rhizobacteria and plant-pathogenic bacteria. High levels of auxins have the potential to impede plant growth. Additionally, certain environmental factors can enhance auxin activity and impact the activity of plant growth-promoting rhizobacteria (PGPR).ResultsIn this work, we boarded how the auxin-like effect in the soil–plant system modulates the plant growth-promoting activity of Lysinibacillus pinottii sp. nov. PB211. The effect of humified organic matter (HOM) soil was simulated with humic acids (HA) coming from vermicompost; the spectral configuration (13C-CP-TOSS-NMR and FTIR) and coleoptile elongation test indicated its bioactivity. Cucumber exhibits a PGP effect of PB211 and HA at a lower concentration compared to corn. This disparity agrees with the differential sensitivity to auxins of both plant models. Monocot plants, such as corn, generally exhibit greater resistance to exogenous auxin activity compared to eudicot plants, such as cucumber. The presence of HA in the growth substrate (sand) is found to modulate the PGPR activity of PB211, resulting in a loss of PGPR activity.ConclusionsThe findings highlight the importance of considering the cumulative auxin-like effects in the soil–plant system when utilizing bacterial inoculants for plant growth promotion in agriculture.Graphical

Molecular mechanisms of seed germination in Hippophae rhamnoides L. based on transcriptomics

Hippophae rhamnoides L. is extensively distributed throughout China and plays a pioneering role in combating desertification and soil erosion in northern regions. H. rhamnoides contains abundant nutrients and is of medical and economic value. However, there has been a lack of research on sea buckthorn seeds, both domestically and internationally, particularly regarding the mechanisms governing their growth and germination. Therefore, to explore the growth of sea buckthorn seeds, this study analyzed and studied the molecular mechanism of seed germination process of sea buckthorn. To better understand the molecular mechanism underlying seed germination in sea buckthorn, we used transcriptomics to compare gene expression before and after seed germination in H. rhamnoides subsp. sinensis Rousi. We identified 9,988 differentially expressed genes (5,593 upregulated and 4,395 downregulated). A bioinformatics-based analysis revealed that changes in plant hormone signal transduction and starch and sucrose metabolism-related gene expression may regulate seed germination in this species. Notably, the levels of auxin (IAA), cytokinin (CTK), and brassinosteroids (BR) increased during seed germination while those of ABA decreased. Exogenous application of IAA, CTK, and BR promoted sea buckthorn seed germination, while ABA inhibited it. These findings suggested that hormones play an important role in the process of sea buckthorn seed germination. This study provides preliminary information about the seed germination mechanism in sea buckthorn, offering an essential reference for improving seed breeding and germplasm and laying the foundation for further resistance research on the molecular mechanism of seed germination of sea buckthorn in this species.

The Arabidopsis splicing factor PORCUPINE/SmE1 orchestrates temperature-dependent root development via auxin homeostasis maintenance.

Appropriate abiotic stress response is pivotal for plant survival and makes use of multiple signaling molecules and phytohormones to achieve specific and fast molecular adjustments. A multitude of studies has highlighted the role of alternative splicing in response to abiotic stress, including temperature, emphasizing the role of transcriptional regulation for stress response. Here we investigated the role of the core-splicing factor PORCUPINE (PCP) on temperature-dependent root development. We used marker lines and transcriptomic analyses to study the expression profiles of meristematic regulators and mitotic markers, and chemical treatments, as well as root hormone profiling to assess the effect of auxin signaling. The loss of PCP significantly alters RAM architecture in a temperature-dependent manner. Our results indicate that PCP modulates the expression of central meristematic regulators and is required to maintain appropriate levels of auxin in the RAM. We conclude that alternative pre-mRNA splicing is sensitive to moderate temperature fluctuations and contributes to root meristem maintenance, possibly through the regulation of phytohormone homeostasis and meristematic activity.

Identification of novel inhibitors of plant GH3 IAA-amido synthetases through molecular docking studies.

Auxins play a critical role in several plant developmental processes and their endogenous levels are regulated at multiple levels. The enzymes of the GRETCHEN HAGEN 3 (GH3) protein family catalyze the conjugation of amino acids to indoleacetic acid (IAA), the major endogenous auxin. The GH3 proteins are encoded by multiple redundant genes in plant genomes, making it difficult to perform functional genetic studies to understand their role in auxin homeostasis. To address these challenges, we used a chemical approach that exploits the reaction mechanism of GH3 proteins to identify small molecule inhibitors of their activity from a defined chemical library. The study evaluated receptor-ligand complexes based on their binding energy and classified them accordingly. Docking algorithms were used to correct any deviations, resulting in a list of the most important inhibitory compounds for selected GH3 enzymes based on a normalized sum of energy. The study presents atomic details of protein-ligand interactions and quantifies the effect of several of the identified small molecule inhibitors on auxin-mediated root growth processes in Arabidopsis thaliana. The direct effect of these compounds on endogenous auxin levels was measured using appropriate auxin sensors and endogenous hormone measurements. Our study has identified novel compounds of the flavonoid biosynthetic pathway that are effective inhibitors of GH3 enzyme-mediated IAA conjugation. These compounds play a versatile role in hormone-regulated plant development and have potential applications in both basic research and agriculture.